Astron. Astrophys. Suppl. Ser. 130, 215-222

Effective temperatures of Ap stars

N.A. Sokolov ^1,2

Send offprint request: N.A. Sokolov (first address)

1 - Central Astronomical Observatory at Pulkovo, St. Petersburg 196140, Russia
e-mail: sokolov@gao.pnpi.spb.ru
2 - St. Petersburg State University, St. Petersburg, Russia

Received September 9; accepted December 3, 1997

Abstract:

A new method of determination of the effective temperatures of Ap stars is proposed. The method is based on the fact that the slopes of the energy distribution in the Balmer continuum near the Balmer jump for "normal" main sequence stars and chemically peculiar stars with the same $T_\mathrm{eff}$ are identical. The effective temperature calibration is based on a sample of main sequence stars with well known temperatures (Sokolov 1995). It is shown that the effective temperatures of Ap stars are derived by this method in good agreement with those derived by the infrared flux method and by the method of Stepien & Dominiczak (1989). On the other hand, the comparison of obtained $T_\mathrm{eff}$ with $T_\mathrm{eff}$ derived from the color index (B2-G) of Geneva photometry shows a large scatter of the points, nevertheless there are no systematical differences between two sets of the data.

Key words: stars: chemically peculiar -- stars: fundamental parameters